Infestations of headlice and other parasitic insects are a perennial problem, particularly in schools where the lice are easily transmitted from child to child. Up to the present time there has been very little that one can do to prevent a child from being infected with headlice. Regular inspection to identify nits, which are the eggs of lice, is the only way to detect an infestation. Treatment includes combing the hair with a fine-toothed comb and/or washing the hair with a special shampoo which contains chemical substances designed to kill the lice and nits.
However, the shampoos that are currently available to treat headlice typically contain harsh synthetic chemicals such as permethrium, piperonyl butoxide and organophosphates which have been known to cause skin irritation. In the United Kingdom across the counter sales of shampoos containing organophosphates have recently been banned because of health concerns.
A further disadvantage with shampoos is that they only treat the hair at the time of use. They do not prevent the child from being re-infected when he/she returns to school.